﻿using System;
using System.IO;
using System.Security.Cryptography;

using System.Text;

namespace Utility
{
    /// <summary>  
    /// 对称加密算法类  
    /// </summary>  
    public static class Encryption
    {

        public static SymmetricAlgorithm mobjCryptoService = new RijndaelManaged();
        public static string Key = "Guz(%&hj7x89H$yuBI0456FtmaT5&fvHUFCy76*h%(HilJ$lhj!y6&(*jkP87jH7";
        /// <summary>  
        /// 获得密钥  
        /// </summary>  
        /// <returns>密钥</returns>  
        static byte[] GetLegalKey()
        {
            string sTemp = Key;
            mobjCryptoService.GenerateKey();
            byte[] bytTemp = mobjCryptoService.Key;
            int KeyLength = bytTemp.Length;
            if (sTemp.Length > KeyLength)
                sTemp = sTemp.Substring(0, KeyLength);
            else if (sTemp.Length < KeyLength)
                sTemp = sTemp.PadRight(KeyLength, ' ');
            return ASCIIEncoding.ASCII.GetBytes(sTemp);
        }
        /// <summary>  
        /// 获得初始向量IV  
        /// </summary>  
        /// <returns>初试向量IV</returns>  
        static byte[] GetLegalIV()
        {
            string sTemp = "E4ghj*Ghg7!rNIfb&95GUY86GfghUb#er57HBh(u%g6HJ($jhWk7&!hg4ui%$hjk";
            mobjCryptoService.GenerateIV();
            byte[] bytTemp = mobjCryptoService.IV;
            int IVLength = bytTemp.Length;
            if (sTemp.Length > IVLength)
                sTemp = sTemp.Substring(0, IVLength);
            else if (sTemp.Length < IVLength)
                sTemp = sTemp.PadRight(IVLength, ' ');
            return ASCIIEncoding.ASCII.GetBytes(sTemp);
        }
        /// <summary>  
        /// 加密方法  
        /// </summary>  
        /// <param name="Source">待加密的串</param>  
        /// <returns>经过加密的串</returns>  
        public static string Encrypto(string Source)
        {
            if (string.IsNullOrEmpty(Source)) { return ""; }
            byte[] bytIn = UTF8Encoding.UTF8.GetBytes(Source);
            MemoryStream ms = new MemoryStream();
            mobjCryptoService.Key = GetLegalKey();
            mobjCryptoService.IV = GetLegalIV();
            ICryptoTransform encrypto = mobjCryptoService.CreateEncryptor();
            CryptoStream cs = new CryptoStream(ms, encrypto, CryptoStreamMode.Write);
            cs.Write(bytIn, 0, bytIn.Length);
            cs.FlushFinalBlock();
            ms.Close();
            byte[] bytOut = ms.ToArray();
            return Convert.ToBase64String(bytOut);
        }
        /// <summary>  
        /// 解密方法  
        /// </summary>  
        /// <param name="Source">待解密的串</param>  
        /// <returns>经过解密的串</returns>  
        public static string Decrypto(string Source)
        {
            try
            {
                if (string.IsNullOrEmpty(Source)) { return ""; }
                byte[] bytIn = Convert.FromBase64String(Source);
                MemoryStream ms = new MemoryStream(bytIn, 0, bytIn.Length);
                mobjCryptoService.Key = GetLegalKey();
                mobjCryptoService.IV = GetLegalIV();
                ICryptoTransform encrypto = mobjCryptoService.CreateDecryptor();
                CryptoStream cs = new CryptoStream(ms, encrypto, CryptoStreamMode.Read);
                StreamReader sr = new StreamReader(cs);
                return sr.ReadToEnd();
            }
            catch  { return ""; }
        }
    }
}